Environment and Public Works Committee Chairwoman Barbara Boxer says the Department of Homeland Security and the Army Corps of Engineers have put “a huge muzzle” on her and her staff by forbidding them from discussing the locations of hazardous coal ash sites across the country.

"There is a huge muzzle on me and my staff," the California Democrat told reporters on Friday. “They’re putting ridiculous restrictions on me.”

Coal ash — a byproduct of burning coal — is full of highly toxic chemicals that can cause birth defects, cancer and other health problems. The toxins can also infiltrate water supplies and destroy fish, bird and other animal populations around the dumps. Some studies have found coal ash to be more radioactive than nuclear waste. But the real danger comes from spills: Last December, a coal ash spill sent a billion gallons of toxic sludge across 300 acres in East Tennessee.

The EPA has identified 44 “high hazard” sites, but the DHS says that revealing their locations could be a security hazard. The agency wouldn’t detail their security concerns, said Boxer, but forbid her from discussing the sites with anyone other than senators from the affected states. No aides, except for Senate Environment and Public Works Committee staff, can be informed.

“It’s very difficult, because you want to take action; you need help to move forward,” said Boxer. “The kind of community response that I believe is positive in these circumstances is just not going to happen right now.”

Boxer is sending a letter to both the DHS and the Army Corps, pushing the agencies to publicly release the information and requesting more details about the security issues surrounding the sites.